Do I need open every http handler for thread safe operation?

[davyzhang]

[mattn]

did you try below?

db, err := sql.Open("sqlite3", "file:locked.sqlite?cache=shared&mode=rwc")

[davyzhang]

so shared cache changed locking mode somehow, Thanks mattn, I will try your fix
I found the doc in sqlite3:

2.1 Transaction Level Locking
At most one connection to a single shared cache may open a write transaction at any one time. This may co-exist with any number of read transactions.

[mattn]

I'm not untra expert about locking of sqlite3. do you have any suggestion to fix this?

[davyzhang]

So far as I can tell, using shared cache and wal will make transaction faster, and avoid "many" errors.

But not all of them, I still can see "data base locked" error in my log, but much fewer than before

[davyzhang]

very dirty test for reproduce the problem
https://gist.github.com/davyzhang/1392344f993eac471c90

not working on my ssd mac pro
but very soon will exit when run my aws micro vps with mag disk

usage dbtest 0/1

it will locked no matter use 2 connections or single connection.

[mattn]

Could you try to add &_busy_timeout=9999999 to connection string?

[davyzhang]

I updated the gist, but... seems no help here still lock error

currently the only solution comes to me is using mutex to seperate reader and writer access. Which is not as described as in sqlite's thread mode doc.

I guess the go's thread mode is bit more different than c, might break the sqlite internal lock mechanism

[Compufreak345]

@davyzhang Did you get any new information about this issue? I've got the same problems.

[davyzhang]

@Compufreak345 Sorry, bad news. I think golang is not a suitable language for sqlite, especially writing http server applications. Thread model is different, like I guess.
I switched my app to mysql/mariadb later after this lock issue, works fine.

[roxma]

@davyzhang

According to #274,

It seems db.SetMaxOpenConns(1) or _busy_timeout would be helpful.

[gjrtimmer]

TODO: Add db.SetMaxOpenConn(1) to README